Monday, September 27, 2010

On Assignment: Radio Silence

Last Friday I went out just before sunset to set up and shoot a lit photo of the Wilkins-Rogers flour mill in Ellicott City, MD. It's a behemoth of a building (at least by our local industrial standards) and I was shooting a exterior for their new website.

My plan was to sculpt the building on the rear 45's with flash. And to balance everything (flash, ambient dusk and interior lighting) for a cool, mixed image. At least that was the plan going in.

Instead, this post is about what happens when things head south quickly. __________

A Brief Window

To appreciate the events that led up to my walking around the parking lot of this mill cursing like a sailor, it helps to understand just how tight the window is to make a three-variable photo. So let's run that down first.

There are three light sources in a flash-lit, dusk shot of an interior-lit building. You have the flash, which is constant and controlled by the aperture (of, of course, ISO/power level/distance.) You have the inside ambient, which is constant and at a fairly low level. And you have the outside ambient which will be dropping -- and very quickly -- by the time all three come together.

Here's how the three-way dance works. First, you choose an ISO/aperture combo that you can hit with your flash. Since my flashes (Profoto B600s) were to be ~100-300 feet away from the surfaces they were lighting, I went with ISO 800 at f/4. That ISO looks great on a D3, and combined with f/4 it gives me lots of range on the flash.

Once you have the ISO and f/stop, you'll need a shutter speed that gives you your (constant) interior lights the way you want them. And that is your exposure setting. You shoot at that setting as the fast-declining sky / outdoor ambient passes through that exposure range and go with the best shot during the crossover.

It is not like shooting flash / sunset ambient mix, where you can shoot at a constant aperture and walk the shutter down to compensate for the sky. (More detailed post on that here.) Your exposure is determined by both the flash and the constant ambient level of the interior lights. And your post-sunset light is dropping fast. So the whole thing only works for a few minutes as they all come together.

You can start testing your flash as soon as the ambient light level hits the target ISO and aperture at a speed at which you can sync. Here is a building flash test (from the position of the first strobe) at ISO 800, f/4, 1/125th of a sec. This is telling me that I can easily paint the building with flash. And now I have a few minutes to adjust my second light before the ambient drops to a shutter speed in the multi-second range at which I will balance all three.

This was a welcome sight. I could evenly paint my end of the building at half power. I was good to go. I put a PocketWizard on the pack and started to walk to my shooting position, about 300 feet away. You can guess what happened next.

I tried a test pop at the shooting position to get the look of the subtle back/rim light I was creating.

So I walked back towards the flash and the PW would not sync until I got about 50 feet from the flash. Even swapping out everything, I could not get the PW to best that 50 foot range.

This is not normal for a PW +II, by a long shot. They routinely give me lots more range than that. But that is the thing about radio. Every now and then the Radio Gods are going to look down at you and press the "smite" button. And tonight, they had the button pushed down and on repeat.

At this point I was walking around, muttering the same phrase to myself, more and more loudly. Suffice to say I sounded a lot like Sawyer from Lost [NSFW-audio].

Do as I Say, Not as I Do

Radio is a fickle lady. And occasionally it will get completely borked on you with no explanation whatsoever. I have learned to hedge my bets for really long-range remote syncing with multiple receivers and piggy-backed slaves. (Here is an example of both being used at extreme range.)

And in this case I could have easily mounted an SB-800 on camera and stuck another SB set to optically slave near the Profotos. The SU-4'd SB-800s are way more sensitive than the slaves in the Profotos (and most other slaves, truth be told.) But I only had one '800 with me, and even in the dark it would not trigger the Profoto slave at ~300 feet.

You'd think I would know to just keep a few extra '800s with me. Lord knows I use them enough. But they were at home in the gear closet. (Why would I bring speedlights to shoot a humongous building, amirite?)

Indeed.

Or, I could have bridged the PW receivers closer with a thick, 100-foot mini-to-mini sync cord (or a mini-extension cord) which I bought from Monoprice for under $20. That was sitting on the shelf in the gear closet about two feet from the SB-800s.

Or, I could have had an assistant at the Profoto pack and had him/her press the test pop button some time within the ~8-second final exposure. (No assistant tonight.)

In short, lots of easy but unavailable solutions. And since I had never been bitten before in this particular way, I was unprepared. And the clock was running fast. So I dropped back and punted.

Light it Later

At the last moment I decided to shoot it available light, with what can best be described as a poor man's selective HDR. I shoot on RAW, which gives me the ability to alter the exposure after the fact. And in doing that, you can blend multiple exposures into one frame.

Here's a straight .jpg (top) from the RAW shot as it came out of the camera, and my final image below. The top exposure was chosen to balance the building and the sky as best I could when the interior lights were glowing. And combining multiple versions of a photo shot in RAW is way easier than you might think if you have never done it before.

I bring the RAW image into Adobe Camera Raw and open it up to a brighter exposure before bringing it into Photoshop. Then, I bring in a darker version (say, for a better sky) and cut-and-paste it on top of the lighter version.

You now have two layers -- dark on top and lighter underneath. With your eraser brush set to a low opacity (I like ~20%) you can slowly and selectively erase the darker building on top to the lighter version below. You can sculpt it almost as if you were lighting it. But you can only work two-dimensionally, which is never really as good as lighting.

Bear in mind that the straight .jpg up top of the duo is the compromise exposure. The imported dark version is darker and the light version is lighter. And going through a few rounds of this import-and-selective-erase process allows me to build a subtly toned exposure that is close to what I want -- even without the flashes.

A Little Perspective

Because of the subject's size and my shooting position, I had to shoot the building with my 18mm lens. Which is not great as far as barrel distortion goes. I got it as close as I could with the lens-distort filter.

Ditto the after-the-fact shift applied, too. Not perfect (the view camera folks will certainly look down their noses at it) but fine in this instance for how the photo will be used. I am strongly considering getting a 24mm tilt/shift lens, which is much straighter on the barrel distortion, too.__________

For the record, I decided to throw this near train wreck out into the open to make three points:

1. I am not a purist when it comes to flash. Or anything, for that matter. Back me into a corner and I will bite, kick, throw sand -- whatever I can do.

2. Things do not always go well for me. Nor will they always go well for you. See #1 above.

3. Be willing to drop back and punt. Even after multiple setbacks, you can often salvage a situation.

I am going back to shoot the interiors soon, and I am really excited about that. I love having a job that gives me the privilege of access to interesting people and places. Especially smaller, interior places where radios work great.

AndI fully expect that shoot to go off as planned. Or a lot closer than this one did, anyway.__________

I have encountered PW sync problems ONLY when shooting in industrial areas. I am convinced that high power transformers/electrical distribution, large machinery, and perhaps various radio for trucks and dispatch are causing interference.

Similarly, I have had problems with optical and IR slaves when shooting indoors in dance clubs, or buildings with IR motion detectors for burglar alarms.

Fortunately, I have always been able to punt with cables. The old Paul C. Buff wired CompuScene was great, because it used standard phone cable, but I unfortunately sold mine when I switched to Pocket Wizards!

I was having one of those days today as well..wireless troubles to be exact.

Half of me wanted to pull my hair out cause this post was giving me flashbacks of this afternoon. The other half of me took comfort in the fact that there's other, far more experienced photogs out there unloading a mountain of curse words at the very same time!

The building may have popped a bit more if it were lit, but the final pic looks great all the same. Better, in fact, since using the profotos wouldn't have been very strobist of you ;)

Thanks for sharing your learning experience with us! I wonder if some part of the flour mill process generates a bunch of "radio noise" that was swamping the PW's at that range? If this is the case then it might also be an issue inside too.

Something to consider for the post technique... it might be better to mask the layers rather than erase them since masking is easier to undo and/or fine tune.

this pretty much sounds like every job I shoot! The constant wrestling with the mountains of gear that decide to work in some completely incomprehensible and unpredictable way is what keeps me on the job! thanks for reassuring me that the photography gods aren't singling me out....I guess the rain does indeed fall on everybody.

* Set up the D3's intervalometer* Set up the SB-800 to fire outside of the frame, but so that you can see it from the Profoto* Have good shoes* Click* Run 300 feet in less than 28s! (at ~7.3mph)* Press the test button on your Profoto in a 8s window after you've seen the SB-800 being triggered

I have been silently appreciating your blog for a long time. I had to comment on this fabulous post, though!! One of the things I think all photographers must have in their camera bag is problem-solving skills. Way to use yours and way to be sincere enough with your audience to help us learn from it. You're awesome!

I have been silently appreciating your blog for a long time. I had to comment on this fabulous post, though!! One of the things I think all photographers must have in their camera bag is problem-solving skills. Way to use yours and way to be sincere enough with your audience to help us learn from it. You're awesome!

and to all the backseat quarterbacks out there, I thought about all kinds of similar ideas reading this as well.

But having been in end of daylight situations like this myself, I know that this is a pressure cooker situation as you're juggling plates, for ambient, for flash, for the cameras exposure. As David pointed out, it was just a simple walk the shutter situation.

So you're out there on the field, and while running to the pack and triggering it at the 50ft mark might work, by the time he gets back to the camera, notices he needs to adjust the blend of light, makes the adjustments and then sprints to try again, he'd probably miss it again as the target doesn't stop while you make changes...

Shooting end of daylight is a real pressure cooker IMO, and I'd have punted too.

Nice recovery, DH. I had a similar situation this summer while shooting the closing ceremony of a charity golf tournament. I setup my flashes in the big room before hand, and everything worked fine. When the speaker started talking... nothing. Test button on the flashes fired just fine, but no radio signal from the transmitter on the camera. I ended up shooting the entire thing unlit at high ISO. After the ceremony, everything worked fine again. I'm assuming that the wireless mic they used interfered with my radio triggers (Cactus V4). If I shoot that event next year, I'll hardwire one flash & use an optical slave on the other.

I suppose hitting the trigger and sprinting to manually fire the pack was probably out of the equation even with a 8 second exposure... Just thinking ahead for next time your stuck in shanghai-ville. Of course with that long of an exposure if you ran thru a corner of the frame you probably wouldn't really register in the final exposure.

Eh, Flour Mill you say?Remember that experiment in second year science class, High school, where the tin of flour blows it's lid?Are they OKay with you taking 1) Radio sources2) Hot lightsinto potentially explosive environments?

David, I am a REALLY old fart and, in the traditon of O. Winston link, I use large reflectors that will hold up to 16 FLASHBULBS each. My brother the electrician actually built the things. I use radio to fire the various banks. Well, sometimes the radio works, sometimes it doesn't, just like in your case. Regarding Joey L, sure, I respect his work, but my question is where does he get the bucks to "travel the world" in search of photos? When I was his age if a trip around the world cost a dime I couldn't get past the corner. Still can't go very far after 55 years-hope you and your followers have better luck :) Love your blog!

Thanks for sharing this David. Glad I'm not the only one who sometimes has to skip plan "B" and resort to plan "C".

One comment I would like to make about your upcoming shoot....

Will you be allowed strobes inside the factory? If there is flour dust in the air there is the concern that it could "flash/explode". You might want to bring some LED panels just in case you can't use your strobes. If you do a search for "Flour mills NFPA rating" you will see what I am talking about with the occupational hazards. (I have been following your blog for a couple of years now, and I'm not trying to psyche you out, but I spent a year designing fire protection systems and know a little about that stuff)

As far as the triggers, have you ever tested the cybersyncs? I modded my 430ex's and 580ex to take a "mono headphone" style jack and have very few issues with that setup (except the one time I put the battery in the transmitter backwards)... readily available cable from any radioshack...

I realize the title is a play on words and not intended to describe the root problem David encountered, but I see enough in the comments about the "RF" issue to jump in and clarify that most RF issues have to do NOT with "silence" but "loudness" in the form of noise.

Most people really don't care about why, but I think it is only fair to the manufacturer to state that this is not likely their problem. No more than the crappy pictures my Nikon D3x takes is Nikon's problem.

There is probably so much RF happening around the building that the PWs are just not able to pick out the signal they are looking for. Bringing the transmitter in close increases the power of the signal. Hey, that inverse square law applies to radio waves just like it does to light! Have a think about how many times David had to DOUBLE the power of the signal before the PW's worked!

If you don't follow the idea of signal-to-noise (and really gang, the same issue is at play in the world of light), then think back to the era of broadcast TV and Radio. Remember how you had to adjust the antenna sometimes to get a clearer picture or sound? All that noise was the result of the signal not "getting through" to the TV or the radio because of "interference"

So lets focus on how David recovered the shoot. IMHO, that is the important message of the post.

Yes, good post. I think most of the time you can learn more from your setbacks than you can from your victories.What was the ground covering?I ask because I had a similar problem shooting in someone's driveway that was covered with a metal smelting byproduct called "slag". When I set my AcuteB on the driveway it would not fire even at 10 feet from the transmitter. When I moved it onto the person's lawn away from the driveway everything worked fine at the usually great Pocket Wizard triggering distances. I know that my metal lightstands sometimes limit the PWs, so I'm assuming that all the metal in the driveway just dissipated the radio signal too much.

"And tonight, they had the button pushed down and on repeat..."that's really cracked me up :D Good job on recovery though, DH. I've had my radio trigger only a few weeks and they've bailed on me randomly more than once. My trusty reflector came to the rescue though. Didn't quite achieve the result I envisioned, but at least got me some "safe" shots that I know the client will like.

Hi David. I had a similar experience last year. I eventually found that there was a high tension electrical wire near the area I was shooting and that affected the signal of my remote trigger. Some electrical field within the area around must have affected your PW. Kudos to your quick thinking.

Great post and it's so true that some times you need to punt. I fill in as the quick & dirty photographer at work some times and don't have access to their Nikon D3 & Photogenic strobes (while my D3 and SB900s are at home). Gotta, as they say, "Think outside the box!"

While I do keep a Nikon D5000 and 18-200mm at work I still gotta get some light somehow ... I've used car lamps, flashlights and even those emergency egress lights with the test button taped down. I even used a SB400 and Mylar covered ceiling lay-in panels as reflectors to paint a machine room once. But it usually works well enough for the intended use of the photograph.

I'm really curious about one thing: how do clients react to such open accounts of your work experience? Especially in cases like this one?

I can imagine that even if the client was originally happy with the end-result, any managerial type reading such an account, might look scoff at your "unsuccessful session" and demand you redo the shoot.

Your problem is most likely related to another radio transmitter on the same channel or an adjacent channel. In an industrial environment there could many different transmitters effecting the success of transmission of the signal to your flashes. Working all days with wireless in industrial applications I would have been surprised if the long range should have succeeded as the PocketWizard most likely has a low output power. This is like trying to whisper to some one that is yelling, it is not much meaning. The shorter the distance, the more likely to get a successful transmission.

Just got back from the Toronto Westcott lighting workshop with James Schmelzer. Excellent presentation about how to position a light and why: rembrandt, broad, split, short, butterfly, etc. and information about concealing faults in the subjects appearance.

The program begins at 5 with a Westcott person talking about qualities of light: hard/soft, and other things Strobist readers already know. Unfortunately, he doesn't understand that in-camera white-balance adjustments have no effect on the raw image, only the preview; that in-camera jpeg previews are inferior to what you generate with Lightroom and in any case an straight-from-the-camera needs some sharpening; and he doesn't understand the difference between specular light and high-contrast lighting. The warm-up presentation is followed by an opportunity to shoot a pretty model under Westcott's daylight flourescent continuous lighting systems, but unless you never get a chance to shoot attractive women, you might as well skip that horny-guy-with-a-camera situation. Anyway, why take photos BEFORE the main presentation, except to have a 'before' example to compare the better photos to!

So my advice, don't rush to the hall, enjoy your supper, and arrive about 7:00 or 7:15, for a 7:30 presentation.

It doesn't matter what material they had in the ground. Radio frequencies can bend around nearly anything, so something on the ground will not block the transmission.

What probably actually happened was that the steel reebar in the building acted as a box. Maybe there was a concrete structure behind you? RF doesn't work well in a metal box. If that was the case you may not have much more luck inside the building.

OR Maybe it isn't a flour factory at all and rather is some kind of secret Gov't building with a RF jammer like one I have played with: http://www.sesp.com/StationaryJammingSystems.asp

Ah, and to think people give me a hard time when I religiously carry three 800's and two J-clamps to each and every shoot. I see them as the best last resort ever, always handy in a pinch.

This is a great post David, without sounding sarcastic, it's always inspiring to see the rougher shoots from pro's, there is this perception that once you are a well-known pro shooter, the screw-up's cease to happen.... so truly not true.

Great post, thanks for the info! As for those radio Gods, I feel your pain; why they choose to hate us at the worst times is beyond me. . .

You often mention that you will adjust your WB to suit a particular scene. Yet this is the first time (since I've been reading) you expressly mentioned that you shoot in RAW. (I assumed you did - no brainer).

Obviously, shooting in RAW, you can ajust your white balance in ACR (or whatever software), so it doesn't really matter what your camera is set to when you take the photo.

Is your tendency to set white balance as you shoot just about 'getting it right in-camera' or am I missing something?

This is (atypically, for me) an available light scene. So I am going to WB it all in the way that it looks best. I shoot RAW +.jpg, so the RAW will write a file that can be adjusted afterwards, but the .jpg will allow me to see my chosen WB at the time.

When shooting flash, I am shooting on daylight WB probably 98% of the time.

I'm not glad you bleed. Who wants more blood? But I am glad you're man enough to tell it like it is/was. We need more men.

As an RF kind of guy, I can tell you that, like lightning, every now and then RF does what it wants, when it wants - probably just to let us know we're not The Boss. Without an RF spectrum analyzer... might as well go ahead and blame anything/everything.

Having lots of steel around (rebar, steel driveways, whatever) can cause multipath echos that the radios can't differentiate from the original signal, ergo you're causing your own noise - in addition to whatever noise there is around you.

As for getting RF to "work right" - one big help would be if the cameras could use their own isolated chunk of the spectrum, like cell phones do, instead of using the free unlicensed bands (433mhz, 900mhz, 2.4ghz, 5.8ghz, etc). But since there's a huge price tag to the FCC for that, don't hold your breath.

This is a technique I use a lot, but instead of playing with the opacity of the history brush or the eraser, I'll just leave the area that I want to tweak, and will then play with the layer opacity...I've found I have more control, and I love the results.

Also, I don't know if the D3 does this, but I accidentally found out the 5Dmk2 will shoot all three bracket photos if you set the camera to self timer.

Any Radio Frequency trigger with a vertical antenna sticking out is omni directional spreading its signal in a circular pattern. If you take a small piece of aluminum foil equal in length to the antenna, fold and crease at a 90 degree angle, and place it behind the antenna the part of the signal coming off the back moving away from the subject will reflect towards the subject increasing the signal strength the receiver. The technical term is called gain! You could also attach a small wire at the base of the antenna to form a counterpoise. Ugly yes and it works

If you're blessed with owning a D3 I guess you can get away with just using one exposure and then using a few different Raw-exposures. If you, like me, own a camera with a bit more meager dynamic range (in my case the D200) I highly would recommend using the bracketing feature to get some more shots at different exposures. Actually, I would always recommend you to use it in a situation like this...just in case.

I had to use this myself for the first time the other day because of the very tuff lighting conditions. In the end I hade to stitch four different images together to get something decent...to make matters worse I couldn't use a tripod since I was hanging out over the edge of a building :)http://www.flickr.com/photos/wagasuki/5067485486/